[css-gaps-1] Values after an auto repeater when there's fewer values than gaps

[kbabbitt]

In #11492 we resolved that, if the number of gaps is less than the number of values provided and there's an auto repeater, we would first use values before the auto repeater, then use values after the auto repeater, then use the auto repeater to fill in any missing values. For example:

column-rule-color: black repeat(auto, red blue) white;

would result in "black" if there's 1 gap, "black white" for 2 gaps, "black red white" for 3 gaps.

What we did not touch on in that discussion is how to handle these edge cases when there are multiple values after the auto repeater. For example:

column-rule-color: black repeat(auto, white) red green blue;

What I wrote in the spec was to prioritize the trailing declarations from last to first. So we'd have "black" for 1 gap, "black blue" for 2 gaps, "black green blue" for 3 gaps, "black red green blue" for 4 gaps, and then we start filling in "white" from the auto repeater.

However, in discussion among the feature team, some folks found this counterintuitive: Since the leading values and auto repeater values should clearly be used from left to right, they expected that we would do the same for the trailing values: "black red" for 2 gaps, "black red green" for 3 gaps, "black red green blue" 4 for gaps.

The use case I had in mind was footers in a data grid. In such a case, I thought authors might want the last few decorations to apply if there's too few rows, rather than "the first of the last." But I can also see how that's inconsistent, and as far as I know it's not a precedented behavior, so I can understand how it might not be what's expected.

What do folks think?